Binder Post, Brass

Small brass connector post similar to those used in early radios. Includes custom threaded 0.15 inch diameter base screw and thumb wheel top for tightening wire. Wire opening is 0.1 inch and accommodates old style headphone plug terminals.

Capacitor, 365 air variable

As the surplus for 365pf caps has dried up, these little beauties are getting harder and harder to find. Not anymore! The Society now has a plentiful supply; we have them manufactured. They are brand new caps, 31 blade, .010-air-gap, 1/4" tuning shaft, and CW rotation decreases capacitance. Testing indicates a capacity range of 390 (fully meshed) to 16 pf. Shaft accommodates the point knob shown (sold separately).

Connections. The frame of the capacitor is connected to the rotor plates and electrical connection must be via a solder lug (or other arrangement) with a 6-32 screw in the bottom or side of the frame. (The 1920s units were this way!). The fixed plates connect to any of the four solder lugs installed in the little brown phenolic boards on each side.

The cap can be panel mounted from the front or on its base via pre-taped 6-32 holes. The spacer shown (and sold separately) enhances mounting the cap via its base. Without a shim or spacer, the phenolic connector boards at each side may be broken when tightening the mounting screws. The spacer fits between the phenolic (pcb) legs and matches up with the holes in the bottom of the cap. Machine screws must be 6-32 by 3/8ths or ¼-inch, depending upon the thickness of the mounting surface. (Screws are not provided.)

Capacitor, 365 air variable with 8:1 reduction drive shaft

This variable cap is exactly like our 365 listed above but includes an 8:1 reduction drive, embedded in the shaft. It's part number is 365-8-1.

What's a reduction drive? It's a mechanical device wherein the plates of the capacitor turn at a slower rate than the attached knob. With this assembly it takes four rotations of the knob to turn the 365 cap from max to min capacitance. Thus a very small change in capacitance is easier to achieve.

Electrical Connections. The frame of the capacitor is connected to the rotor plates and electrical connection must be via a solder lug (or other arrangement) with a 6-32 screw in the bottom or side of the frame. The spacer listed above fits the 365-8-1 too. The fixed plates connect to the two solder lugs installed on the brown phenolic boards on each side.

Capacitor, Dual Gang air variable

The 1/4-inch shaft rotates both sections of rotary plates simultaneously, and each is grounded to the general case - and is thus a common connection point via the frame with screws/lugs. Each section of stationary plates has separte solder lugs and mica trimmers. Mounting is with 6-32 machine screws via dimpled standoff holes on the bottom.

Planetary Reduction Drive, 6:1 (05/03/08 temporarily out of stock, check back.)

This add-on reduction drive rotates the shaft of an attached device - such as our 365 capacitor - at 1/6-th the turning rate of the front panel knob. The shaft of the driven device is secured by set-screws in the enlarged output shaft of the drive, and the drive is mounted with an L-bracket via the two "wings" as shown in the picture. The input shaft accommodates a 1/4-inch knob.

This drive can be combined with our 365-8-1 capacitor for a gigantic reduction in cap plate ratation of 48:1!

Capacitor assortment

This ceramic cap assorment includes two each of caps commonly found in crystal sets, as per the table. A sheet on how to identify labeling on the capacitors comes with the assortment.

Catwhisker, Phospher Bronze

Small wire with wound springy end for "catwhisker" replacement in a detector stand. Generally one screws the wound (springy) portion of the whisker onto a threaded shaft. The other end is pressed against a mineral, such as galena.

Coil Forms

These PVC & ABS plastic pipe forms are pre-cut and pre-drilled, ready for you to wind coils. Each kit contains 3 pipes, 6@ 6-32 metal screws and 6 nuts, and a coil information sheet. You may wish to use nylon (non-conducting) nuts & bolts to install the forms in a set. See Nylon-Parts. Also see the Coil Calculator to determine number of turns for a target inductance. As with wood, actual diameter of pipe is not the same as that called out or printed on the pipe. Physical outside diameter and length for each form is listed below.

Diodes, 1N34:    The 1N34 has radial leads and a glass housing. Dark ring on one end denotes the "negative" side.

Earplug, Crystal

High impedance crystal earphone with tinned ends. Use in place of old-style hi-impedance headphones. Place a 47K or greater resistor across the earplug leads.

Fahnestock clips:   Used to connect antenna, earplug, or phones to a set. Fits 6-32 nut and screw (not provided).

Galena Crystals

We offer galena crystals in a 0.475 inch diameter woods metal mounting or raw. Each mounted crystal has been tested. The mounting fits nicely in many old style detector stands. Crumpled aluminum foil and a wire jammed into a hole can offer an alternative way of mounting.

Inductors, Miniature

Packs include 4 molded RF chokes (that look like resistors), suitable as coil substitutes for making miniature crystal sets. Just think; you can make crystal sets without winding a single coil. Q will be somewhat less than when using wire wound coils. Packs include a sheet on several possible projects to build. The L-Pack includes one each as in the table. The 250-pack includes 2 33 uH and 2 250 uH molded coils.

Knob, Pointer

This knob fits on a ¼-inch shaft; hence, it fits our 365 single and dual gang air capacitors and panel mount pots. Set screw in knob secures knob to shaft. The knob is shown in the picture with the 365 air variable capacitor above.

Potentiometers, panel mount

These potentiometers are ideal for front panel installation. Both log and linear taper 10K, 100K, and 1MEG pots are now stocked. Log taper are ideal for audio volume control and linear taper are useful for diode bias or a Benny, amoung other apps. Pots include three solder lug terminals, 0.25" dia by 0.5" (in front of panel) shaft with threaded base, tit, and nut for mounting, and fit our pointer knob too!

Resistor, 47K:   This 1/4-watt resistor is sued with our earplug in a number of kits, including the Oat Box Kit.

Solder Lugs:   Useful for may connections, including chassis ground. Mounts with 6-32 nuts and screws (not included).

Toroid, FT-82-61

This 0.83 inch diameter toroid is useful when you want to keep coil size small and limit the amount of enamel wire required for a given inductance (coil). The FT-82-61 is suitable for the AM broadcast band and hence for crystal sets. Toroidal coils can be mounted within a set using glue or nylon washers and screws.

Transformer: 1200-to-8 ohm

Transformer useful for matching crystal set to 8-ohm headset or speaker. Primary is 1200 ohms; secondary is 8 ohms. Application sheet included. Normally one would tap down on the crystal set coil when using a 1200 ohm load (from the transformer primary).

Wire: hookup, magnet & Litz:   Coils can be wound with hookup, magnet, or Litz wire. See the January 2008 issue of the Xtal Set Society Newsletter for an introduction to the use of Litz (or woven) wire. Wire diameter and covering are listed in the table.